Gas valves with high speed opening and high speed gas flow capability are required for various uses, for example in cold gas airbag inflation test systems for testing automobile airbags that protect occupants of the automobile in the event of a collision. Specifically, airbag deployment systems basically include an airbag and an inflator. The inflator generates and releases the gas necessary to inflate the airbag. During a collision in an automobile, the inflator is triggered by the destruction of a rupture disc, which releases the gas to fill the airbag in a mere fraction of a second.
Even a small change in the orientation of a vehicle's dash board could have a significant effect on the deployment of an airbag since the deployment occurs so quickly. As a result, many tests must be performed throughout the design or re-design process of an automobile to ensure that the deployment of the airbags meet all regulations or requirements. The rupture discs are permanently destroyed in automobile airbag systems so the airbags must be completely replaced after use. It is therefore not feasible to use actual airbag systems to run large numbers of tests while designing a vehicle.
Instead, a separate, re-usable valve apparatus is desired to simulate the destruction of the rupture disc and subsequent inflation of the airbag. Such a valve must perform consistently and accurately so that it does not skew data being collected or introduce error into the tests. These valves must also deploy extremely quickly to properly simulate actual airbag deployment. A typical simulation gas valve inflator, for example, may need to consistently open a one inch diameter valve in 2 ms. At the present time, suitable gas valves for this purpose do not appear to be commercially available which can properly simulate actual airbag deployment in a nondestructive manner.
For example, U.S. Pat. No. 4,635,855 (Kuyel et al.) teaches a method and apparatus for rapidly controlling a flow of gas which utilizes a conductive disc to seal an orifice of a plenum holding the gas, and an electrode located proximate to the plate. By applying a current through the electrode, an eddy current is induced in the disc, which creates a repulsion force that repels the disc away from the electrode for opening the orifice. However, to open the orifice, the repulsion force must overcome a force due to pressure of the gas stored in the plenum, and therefore, is too slow and inconsistent to be used in an airbag deployment simulation. Furthermore, the apparatus taught in this reference would open even slower, or perhaps not at all, when used with gases having significantly high pressures, as the repulsion force would have to be incredibly high to overcome the force due to pressure.
Similarly, Japanese Patent Publication No. JP58191380 (Kazuo) teaches a gas valve which utilizes induced eddy currents in a plate coupled to a rod to open or close the valve by varying the current passing through permanent magnets located proximate to the plate. Like the '855 patent to Kuyel et al., the system taught in this reference must overcome a force on the plate due to a pressure of the gas, and therefore, is too slow and inconsistent to be used to test airbag deployment. Also like the Kuyel et al. apparatus, the system taught in this reference would open even slower, or perhaps not at all, when used with gases having significantly high pressures, as the repulsion force would have to be incredibly high to overcome the force due to pressure.
It is therefore an object of the invention to provide a gas valve which is capable of high speed opening and high speed gas flow and is also suitable for use in a cold gas airbag test system.